The book I'm trying to find involved unbelievable alien abductions; the kind that you'd mock them if their story appeared on TV or in a magazine. The main character (most likely a teenaged guy, although I don't remember for certain) experiences such an abduction. He probably tries to tell people about it and is promptly shot down, since his story is so unbelievable. He ends up in a meeting or support group or some other gathering of people that had similar experiences.
The similarities are that their stories are all unbelievable, but completely differ in details. The motives, appearances, methods, etc of the aliens are all different for all the people involved in the group. The only commonalities are "Aliens did it" and "No one will believe me".
The main character figures out that this is the point: aliens are genuinely abducting people and basically subjecting them to ridiculous stage plays to ensure that their stories don't add up and that no one will believe them. It's possible it's not actually aliens and is just a bizarre government coverup, but I'm pretty sure it involved real aliens.
One specific scene I remember is that the main character realizes that he has some kind of radio transmitter/tracker embedded in his ear lobe. This wasn't part of the overt abduction, and he had no idea it was in there at first. Presumably all the other abductees also had one and don't know it. After realizing this, he cuts off his ear lobe to remove the transmitter while in a public bathroom. I distinctly recall that a receptionist spots his still-bleeding ear and looks at him like he's crazy - he may have been trying to ask him/her to borrow the phone or something similar - leading to his escaping the building in haste. He was probably trying to escape the (real) aliens at this time and trying to keep a low profile, but the bleeding ear made him stand out in a crowd, even without the transmitter.
I read this around 15-20 years ago. I'm assuming it wasn't much older than that, but I don't remember anything specific about when it was set. It was probably a Young Adult/Teen novel. I don't remember anything about the title, cover, or any other characters, just this general synopsis and the one specific scene with the ear cutting.